Removable energy source for sensor guidewire

ABSTRACT

A transmitter unit with a detachable energy source is provided for a sensor guidewire. The transmitter unit is adapted to be connected to a proximal end of a sensor guidewire provided, at its distal end, with a sensor to measure a physiological parameter inside a patient. In some embodiments, the transmitter unit is adapted to wirelessly communicate by a communication signal with a communication unit, arranged in connection with an external device, in order to transfer measured physiological data to the external device. The detachable energy source can be a battery pack provided with connecting electrical connecting surfaces. Preferably, the connection is protected from penetrating fluids by a protective seal.

FIELD OF THE INVENTION

The present invention relates generally to a removable energy source forsensor guidewires and in particular to a detachable battery pack locatedon or at the transceiver unit in such an assembly.

BACKGROUND OF THE INVENTION

In many medical procedures, various physiological data within the bodyof a patient need to be monitored and analyzed. Typically, these dataare physical in nature—such as pressure, temperature, and flow rate—andneed to be monitored in a safe, reliable and accurate way. In the priorart, it is known to mount a sensor on a guidewire or catheter and toposition the sensor via the guidewire in a blood vessel in a living bodyto detect such a physical parameter. The sensor includes elements thatare directly or indirectly sensitive to the parameter. Numerous patentsdescribing different types of sensors for measuring physiologicalparameters are assigned to the assignee of the present patentspecification. For example, temperature can be measured by observing theresistance of a conductor having temperature sensitive resistance asdescribed in U.S. Pat. No. 6,615,067. Another exemplifying sensor may befound in U.S. Pat. No. 6,167,763, in which blood flow exerts pressure onthe sensor which delivers a signal representative of the exertedpressure. The entire contents of these patents are incorporated hereinby reference for the devices and methods disclosed therein.

The raw signal generated by the sensor located within the body istransmitted to an external device, in which the signal is re-translatedinto physiological data, which is processed and the results continuouslydisplayed on e.g. a monitor and/or saved. In order to power the sensorand communicate signals representing the measured physiological variableto an external device, one or more cables or leads for transmitting thesignals are connected to the sensor, and are routed along the guidewireto be passed out from the vessel to the external device, conventionallyvia physical cables. In addition, the guidewire is typically providedwith a central metal wire (core wire) serving as a support for thesensor and (optionally) also as an electrical connection to the sensor,and a surrounding tubing. Hence, a sensor guidewire typically comprisesa core wire, leads and protective tubing, as well as a distal coil ortube and a jacket housing encasing the sensor.

In order to eliminate the risks of having an electrically conductivedevice such as a pressure transducer connected both to a patient and toan electronic monitoring instrument, a wireless arrangement can be used,e.g. as described in US Patent Application Publication No. 2006/0009817,assigned to the present assignee. In the aforementioned patentapplication, the pressure sensor wire is adapted to be connected, at itsproximal end, to a transceiver unit that is adapted to wirelesslycommunicate via a communication signal with a communication unitarranged in connection with an external device, in order to transfermeasured pressure data to the external device. In addition to theadvantage of electrical insulation, a wireless arrangement decreases theamount of cables and other electrical equipment present in the operatingroom, and also facilitates the use of a standardized communication unitcapable of being connected to a wide range of external devices. Thisobviates the necessity to use a specific external device, possiblydifferent from that which is already present in the operating room.However, in contrast to a conventional sensor guidewire assembly, thepressure sensor in a wireless arrangement is not in electricalconnection with the external device. Therefore, an additional energysource is required, such as a battery or capacitor, to power thetransceiver unit and the pressure sensor. Also in a wired sensorguidewire assembly, a battery can be used as an alternative or auxiliarypower supply. The entire contents of this publication are incorporatedherein by reference for the devices and methods disclosed therein.

SUMMARY OF THE INVENTION

Using a transceiver with an internal battery is not well-suited for usein a disposable single-use medical device intended for an extendedprocedure in a sterile environment, which is the normal situation forsensor guidewires. Therefore, an object of the present invention is toprovide an energy source better adapted to the abovementionedconditions, for use with sensor guidewires and other medical deviceswherein a sensor is inserted into a body cavity for measurement of aphysiological parameter.

The present invention provides a detachable energy source for a sensorguidewire assembly. Furthermore, the energy source is adapted to asterile manufacturing and handling process, and is easily disposable inan environmentally acceptable manner. In addition, the energy source canbe adapted to be detached after completing a procedure, optionallyrecharged, re-sterilized and used in one or more subsequent sensorguidewire procedures. The energy source can be used in a wired orwireless setup in a sensor guidewire procedure.

In some embodiments the energy source comprises one or severalbatteries. The batteries can be enclosed in a sealed holder. The batterypack is connected to a transmitter or transceiver unit whereupon, insome embodiments, the unit is powered up, calibrated and can optionallyindicate by a light or sound signal that the assembly is ready for use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one application of the present invention in a sensorguidewire assembly.

FIG. 2 shows a block diagram schematically illustrating a transmitterunit according to a preferred embodiment of the present invention.

FIGS. 3 a and 3 b illustrate the present invention according to afurther embodiment, in cross-sectional view and perspective view,respectively.

FIG. 4 illustrates the present invention according to anotherembodiment.

FIG. 5 illustrates the present invention according to yet anotherembodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For ease of understanding, embodiments of the present invention aredescribed in conjunction with a sensor guide wire. However, it is alsowithin the scope of the invention to use a detachable energy sourceaccording to the present invention to power a transmitter unit connectedto a sensor mounted on a catheter. Moreover, the transmitter unit is inmany cases also a receiver unit. In those cases, the unit is, in fact, atransceiver unit, wherein the communication with the external device isa two-way communication. Thus, in the description below, unlessexplicitly stated, a transceiver unit can be exchanged for a transmitterunit.

In manufacturing a pressure sensor guide wire assembly, the pressuresensor wire and the transceiver unit must be able to be sterilized priorto use, which in practice has produced problems in the cases where aninternal battery is present. Conventionally, gas sterilization usingethylene oxide is used for sensor guidewires. Specific precautions foreach type of battery need to be taken in order to eliminate the risks ofplacing a battery connected to an electrical circuit in ethylene oxide.The present invention provides an improved sensor guidewire assemblywhich can be sterilized safely and also has environmental advantages.

For ease of description, examples of the present invention areillustrated in conjunction to an internal pressure sensor mounted in awireless sensor guidewire assembly. However, it should be noted that itis within the scope of the invention to use a sensor adapted to measureother physiological parameters within the body, such as flow ortemperature. It is also within the scope of the present invention to usea wired sensor guidewire assembly. Even though conventional, i.e.non-wireless, sensor guidewire assemblies are powered by an externalpower source, the present invention can eliminate the dependency on anexternal power source, or serve as an auxiliary energy source.

FIG. 1 is a schematic overview illustrating one application of thepresent invention. The pressure measurement system according to thisembodiment of the present invention comprises a pressure sensor wirewith a sensor adapted to measure pressure inside a patient, and toprovide measured pressure data to an external device. The pressuresensor wire is adapted to be connected, at its proximal end, to atransmitter or transceiver unit adapted to wirelessly communicate via aradio frequency signal with a communication unit arranged in connectionwith an external device, in order to transfer measured pressure data tothe external device for analysis and display.

The external device may be a dedicated device or a patient monitoringdevice, preferably provided with a monitor, or a PC provided withrelevant software and external connections to receive and to process themeasured data from the pressure measurement system.

FIG. 2 shows a block diagram schematically illustrating the transceiverunit 10 according to one embodiment of the present invention. As shownin FIG. 1, the transceiver unit is adapted to be connected to theproximal end of a pressure sensor wire provided, at its distal end, witha pressure sensor to measure pressure inside a patient. Preferably, thetransceiver unit 10 comprises a sensor signal adapting circuitry 1, acommunication module 2, connected to the adapting circuitry 1, that willhandle the wireless communication with the communication unit via theantenna 3. The communication is preferably bi-directional, but can alsobe one-way.

The measured signal is communicated by the transceiver unit andtransferred as a data stream to the communication unit at a prescribedfrequency range (in the case where the communication signal is a radiofrequency signal). The signal can also be an infrared signal, a lightsignal, an ultrasound signal or any wirelessly transmitted signal. InFIG. 2, the antenna 3 is illustrated as protruding outside thetransceiver unit but may, as an alternative, be integrated into thehousing of the transceiver unit. The pressure sensor wire is adapted tobe inserted into an elongated aperture 4 of the transceiver unit 10. Theaperture 4 is at its inner surface provided with a number of electricalconnecting surfaces (not shown) to be connected to electrode surfaces atthe proximal end of the pressure sensor wire when inserted into theaperture 4. The transceiver unit 10 can further be provided with a wirefastening means or mechanism (not shown) to firmly fixate the wire whencorrectly inserted into the aperture, if the transceiver unit isintended to be used as a torque device, as described below. As analternative, the wire fastening means or mechanism can be constructed tohold the wire securely longitudinally, while allowing free rotation ofthe wire within the aperture 4.

When the pressure sensor wire is fixated to the transceiver unit, theunit may be used as a torque device when guiding the pressure sensorwire during insertion into a patient. Preferably the transceiver unit isprovided with gripping means or structure 5, e.g. in the form of one ormany elongated ribs on the outer surface of the transceiver unit, or byproviding the transceiver unit with a roughened surface. In this contextit should be mentioned that in the figures, the transceiver unit 10 andcorresponding battery pack 6 (described below) are illustrated as havinga generally round cross-sectional shape. However, it should be notedthat it is within the scope of the invention to provide a transceiverunit and corresponding battery pack with any cross sectional shape.Using, for example, an octagonal cross-sectional shape, will provide foreasier manipulation when using the transceiver unit as a torque device.

The transceiver unit is further provided with an attachable anddetachable battery pack 6. Notably, the battery pack 6 is deliveredseparated from the transceiver unit and attached just prior toinitiation of the surgical procedure. The battery pack is preferablyencapsulated to ensure easy sterilization as well as easy transport,handling and connection. The battery pack 6 can be hermetically sealedif desired. The battery pack 6 is also provided with electricalconnecting surfaces 8 constructed so as to fit the correspondingelectrical contact members 7 on the transceiver unit 10. The batterypack 6 can be connected to the transceiver unit 10 by any type ofelectrical connectors to mate electrical connections, such as, but notlimited to, those described below.

In FIG. 2, the connection is illustrated as having extending plugs 7 onthe transceiver unit and receiving apertures 8 on the battery pack 6.However, it is within the scope of the present invention to provide theopposite arrangement, i.e. extended plugs on the battery pack andapertures on the transceiver unit. The extended plugs can moreover haveany cross-sectional shape, as long as the receiving apertures areadapted to accept the extended plugs. Furthermore, the extended plugsand receiving apertures can be constructed such that the extended plugssnap into place when fully inserted, so as to firmly attach the batterypack 6 to the transceiver unit 10.

In a further embodiment, illustrated in cross-sectional view in FIG. 3 aand in perspective view in FIG. 3 b, the electrical connector isprovided with a protective seal 9, preferably sealing the connectionbetween the battery pack 6 and the transceiver unit 10 against fluidsand other material when connected. The seal 9 is preferably elastic andcan comprise rubber, silicone or any other material used to sealopenings against penetrating fluids. Furthermore, the seal 9 is providedwith an inner diameter slightly smaller than the outer diameter of thetransceiver unit 10. The protective seal 9 can be any shape, as long asit seals the section containing electrical connecting surfaceseffectively against penetrating material which could potentiallyshort-circuit the connection. In the types of procedures described here,i.e. when using a sensor guidewire, there is normally blood and otherfluids present and it is important in such an environment to avoidshort-circuiting the system. The protective seal 9 can also beconstructed so as to firmly hold the connector in place. Furthermore,the protective seal 9 can function as a shield against accidentalcontact by the user with the live electrical circuitry.

A further embodiment is illustrated in FIG. 4. As shown, the electricalconnector can comprise electrical connecting surfaces or contact members17, 18 placed flat against the transceiver unit 20 and the battery pack16, respectively, which come in contact with each other when the batterypack is connected to the transceiver unit by any attachment means ormechanism (an example of which is described below). Using flatelectrical contact members provides for easy cleaning of the connectingsurfaces, which is an important characteristic when working withelectrical equipment in a wet environment. Here, the connector isprovided with a protective seal 19 which can also function toeffectively hold the battery pack attached to the transceiver unit 20,and optionally also act as a shield against accidental contact by theuser with the live electrical circuitry.

In addition to using the protective seal as an attachment mechanismusing frictional forces, the battery pack can also be attached to thetransceiver unit by any fastening mechanism, including the embodimentillustrated in FIG. 5. In this embodiment, the protective seal 29 againfunctions as a portion of an attachment means or mechanism. The insideof the protective seal 29 on the battery pack 26 is provided withinternal threads 31 adapted to fit external threads 32 located on thetransceiver unit 30. This embodiment provides very secure attachment,however the design of the electrical connecting surfaces (not shown inFIG. 5) has to be adapted to a rotating attachment procedure. Forexample, the flat contact members illustrated in FIG. 4 can be used inthis embodiment. Other attachment means or structure besides threadsinclude, but are not limited to, snaps, screws and barbs.

When the battery pack 6, 16, 26 has been attached to the transceiverunit, and the communication unit is connected to or integrated into theexternal device, the system is ready for use. According to oneembodiment, the transceiver unit is activated and initiated when thebattery pack is correctly attached to the unit. Upon correct attachmentof the battery pack, the transceiver unit is powered up and preferablycalibrated. In another embodiment, the transceiver unit will then try toestablish a radio link connection with the communication unit. This ispreferably performed by a conventional handshake procedure in order toidentify the transceiver unit. In this embodiment, simply connecting thebattery establishes that the connection is correctly made, that thebattery is loaded and of the correct type and subsequently ensures thatthe system is initiated and ready for use, all in one step. In a furtherembodiment, the transceiver unit indicates activation, and optionallyalso successful calibration and/or connection with the communicationunit, by e.g. a light or sound signal directly following attachment ofthe battery pack.

Battery packs 6, 16, 26 can comprise one or several batteries. Thebatteries can be of a non-rechargeable or a rechargeable type. Thebattery type can be any type in the art, including, but not limited tolithium primary battery, lithium ion (such as lithium iodine, lithiumthionyl chloride, lithium carbon monofluoride or lithium silvervanadiumoxide) battery, alkaline manganese battery, other alkalinebatteries, nickel cadmium battery, nickel metal hydride battery, mercuryoxide battery, silver oxide battery, lead battery, zinc-air battery,carbon zinc battery, zinc manganese battery, manganese dioxide battery,and a capacitor cell.

Using a detachable battery pack, allows for an increased freedom inchoice of sterilization methods during manufacture, as the energy sourceis disconnected from the electrical circuit, and the risks of processinglive circuitry in the sterilization procedure are obviated. A batterypack according to the present invention, i.e. a battery pack which isnot part of a live circuit (in other words, the battery pack isdisconnected from any circuitry and therefore no current is flowing),can be sterilized using any sterilization method in the art, includingbut not limited to gas sterilization, autoclaving, radiation or alcoholtreatment.

Using a detachable battery pack, in addition to making production andsterilization safer, is also positive from an environmental point ofview. A battery pack can be transferred from one transceiver unit toanother, enabling use of one battery pack for several interventionalprocedures. Preferably, the battery pack is re-sterilized and optionallyrecharged before subsequent use. Also, disposal of the battery is madeeasy when using a detachable battery pack.

Manufacture of a sensor guide wire entails calibration and testing ofthe final product before shipping to the user. When producing a sensorguide wire with a detachable battery pack, the manufacturer has theadvantage of being able to use an energy source other than the energysource to be used during the surgical procedure for testing andcalibrating the sensor during manufacture. Thus, the energy sourceneeded for the surgical procedure is not depleted before initiation ofthe surgical procedure itself.

Although the present invention has been described with reference tospecific embodiments it will be apparent for those skilled in the artthat many variations and modifications can be performed within the scopeof the invention as described in the specification and defined withreference to the claims below.

1-19. (canceled)
 20. A method of making a guide wire assembly having apressure sensor wire, a transmitter unit, and an energy source which isattachable to and detachable from the transmitter unit via a fasteningmechanism, comprising the steps of sterilizing the pressure sensor wire;and sterilizing the energy source separate from the sterilizing of thepressure sensor wire while the energy source is detached from thetransmitter unit.
 21. A method as set forth in claim 20, wherein gas isused to sterilize the pressure sensor wire. 22-23. (canceled)
 24. Amethod of making a guide wire assembly having a pressure sensor wire, atransmitter unit, and an energy source which is attachable to thetransmitter unit via a fastening mechanism, comprising the steps ofsterilizing the pressure sensor wire; and sterilizing the energy sourceseparate from the sterilizing of the pressure sensor wire before theenergy source is attached to the transmitter unit.
 25. A method as setforth in claim 24, wherein gas is used to sterilize the pressure sensorwire.
 26. A method of reusing an energy source for a guide wire assemblyhaving a pressure sensor wire, a transmitter unit, and the energy sourcewhich is attachable to and detachable from the transmitter unit via afastening mechanism, comprising the steps of sterilizing the pressuresensor wire; and recharging and sterilizing the energy source separatefrom the sterilizing of the pressure sensor wire before the energysource is attached to the transmitter unit.
 27. A method as set forth inclaim 26, wherein gas is used to sterilize the pressure sensor wire. 28.A method as set forth in claim 20, wherein the energy source is arechargeable energy source.
 29. A method as set forth in claim 20,wherein the transmitter unit further comprises a receiver module, toform a transceiver unit.
 30. A method as set forth in claim 20, whereinthe transmitter unit is adapted to wirelessly communicate by acommunication signal with a communication unit, arranged in connectionwith an external device.
 31. A method as set forth in claim 24, whereinthe energy source is a rechargeable energy source.
 32. A method as setforth in claim 24, wherein the transmitter unit further comprises areceiver module, to form a transceiver unit.
 33. A method as set forthin claim 24, wherein the transmitter unit is adapted to wirelesslycommunicate by a communication signal with a communication unit,arranged in connection with an external device.
 34. A method as setforth in claim 26, wherein the transmitter unit further comprises areceiver module, to form a transceiver unit.
 35. A method as set forthin claim 26, wherein the transmitter unit is adapted to wirelesslycommunicate by a communication signal with a communication unit,arranged in connection with an external device.
 36. A method of making aguide wire assembly having a pressure sensor wire and an energy source,comprising the steps of sterilizing the pressure sensor wire; andsterilizing the energy source separate from the sterilizing of thepressure sensor wire before the energy source is electrically coupled tothe pressure sensor wire.
 37. A method of reusing an energy source for aguide wire assembly having a pressure sensor wire and the energy source,comprising the steps of sterilizing the pressure sensor wire; andrecharging and sterilizing the energy source separate from thesterilizing of the pressure sensor wire before the energy source iselectrically coupled to the pressure sensor wire.